Cluster Support in Sun Java System Web Server 7.0 Update 1

A cluster is a set of instances, spanning across one or more nodes,
all running identical configuration and offering an identical set of runtime
services. Each cluster must include one server designated as the administration
server. If you have more than one cluster, you can administer all clusters
from a single master administration server. The master administration server
retrieves the information about all the clusters and provides the interface
for managing the servers installed in their respective clusters.

Note –

All the instances in a cluster are required to be homogeneous.
For example they run on an identical operating system version (and patches)
and service packs, run an identical web server configuration and offer identical
services.

Setting Up a Server Farm

For setting up a cluster, you need to first install one administration
server and one or more administration nodes. The administration nodes have
to be registered to the administration server individually for them to be
administered. This action can be performed either during installation of the
nodes or after installation through wadm CLI.

To Set Up a Server Farm

Installing Administration Server and Administration Nodes

Install the administration server. You can install the administration
server through Sun Java System Web Server 7.0 Update 1 Installer GUI or through the wadm CLI.

You can choose the Express
installation option, which will install an administration server
on port 8989. Alternatively, choose Custom Installation option
for setting your preferences. To install the administration server, choose
the option Install server as Administration Server in
the installer setup screen. You need to specify the SSL port but may or may
not specify a non SSL port.

Note –

If a non SSL port is specified, an administration node
is created in the administration server node and this need not be registered
with the administration server explicitly.

To install the administration node , choose Custom Installation and then Install server
as administration node. Specify a port for installation. You do
not have an option to select non SSL port as all communication between administration
server and administration node is through a secure channel. During the installation,
you will be asked if you need to register the node with the administration
server. If you choose not to register the node during installation, you can
use the wadm CLI to perform this action.

Note –

You cannot install administration nodes through express installation.

Register the Administration Node with the Administration Server

The administration nodes have to be registered to the administration
server for them to be part of the cluster or the server farm. The administration
nodes will not start up unless they are registered to an administration server.
For registering the administration node execute the following command through wadm CLI.

This port is the one specified during the administration server installation.
Host is the hostname of the node where the administration server is installed.

This action will register the node to the administration server.

Note –

A node can be registered only from the same node . You cannot
go to the CLI of the administration server and register any node. Also the
registration of node with the administration server can be done in SSL mode
only.

Setting Up a Simple Cluster

As part of this example let us set up a cluster with one load balancer,
one administration server and four web server instances with session replication
enabled. Session replication provides high availability for Java web application
sessions. It does so by making copies of sessions resident in memory of one
web server instance to another web server instance. So, in normal operational
conditions, there are at least 2 copies of every session each residing in
a separate JVM and, optimally, on a separate machine.

The following figure depicts a simple cluster:

To Configure Your Cluster

Before You Begin

Identify the following machines:

MachineA — Has both the load balancer and the administration
server.

MachineB, MachineC, MachineD and MachineE — Has the
administration node and the web server instances running.

Install Administration Server on MachineA.

See To Set Up a Server Farm for information on installing
an administration server. The typical installation process will also install
a web server instance. For this scenario, we will not be using that instance.

Install the Administration Node on MachineB, MachineC, MachineD
and MachineE.

Install the administration node on all the 4 machines.
Register the administration nodes with the administration server.